The goal of this work is to understand the genetic and molecular mechanisms leading to disorders that affect the adrenal cortex, with emphasis on those that are developmental, hereditary and associated with adrenal hypoplasia or hyperplasia, multiple tumors and abnormalities in other endocrine glands (especially the pituitary gland and to a lesser extent the thyroid gland). We have studied congenital adrenal hypoplasia caused by triple A syndrome and multiple endocrine deficiencies, familial hyperaldosteronism, adrenocortical and thyroid cancer, pituitary tumors and multiple endocrine neoplasia (MEN) syndromes affecting the pituitary, thyroid and adrenal glands, and Carney complex (CNC), an autosomal dominant disease. CNC is a MEN syndrome affecting the pituitary, adrenal cortex, thyroid, and the gonads, and is associated with a variety of other tumors, including myxomas and schwannomas, and skin pigmentation defects (lentigines, cafe-au-lait spots, and nevi). We have identified the regulatory subunit type 1-? (RI???of protein kinase A (PKA), which is coded by the PRKAR1A gene as the gene responsible for most CNC patients. Thus, a significant part of our work is now focused on PKA-stimulated signaling pathways, PKA effects on tumor suppression and/or development, the cell cycle and chromosomal stability. These projects are facilitated by Prkar1a-specific animal models.